package edu.kjxy.demo0301;

public class HelloCircle {

	public static void main(String[] args) {
		double r = 10.0;  // 半径
		
		double a = Math.PI * r * r; //面积
		double c = 2 * Math.PI * r; //周长
		
		System.out.println("面积:" + a + "，周长:" + c);
		String str = "面积：%.2f,周长：%.2f.".formatted(a, c);
		System.out.println(str);
	}

}
